Work machines, such as skid-steer loaders, track-type machines, excavators, bulldozers, on-road trucks, off-road trucks, and other such work machines are used in a variety of industries such as, construction, agriculture, and mining. Typically, work machines include multiple electronic control input devices such as, joysticks, levers, buttons, dials, wheels, and pedals, which are configured to control and perform various work machine operations. For example, the work machine may incorporate multiple electronic joysticks configured to move the machine forward and rearward, and provide turning and other maneuvering capabilities in a variety of directions. Additionally, the multiple electronic inputs may be configured to further control work tools and other implements that are attached to the work machine and configured to perform a variety of tasks.
In operation, the multiple electronic control input devices may work together in the control and operation of the work machine. For example, electronic joysticks may be one such input device used by an operator to control the movement of the work machine. Each electronic joystick may be actuated in a forward operational position to propel the work machine in a forward direction of travel and/or actuated in a rearward operational position to propel the work machine in a backwards direction of travel. Additionally, each electronic joystick may be actuated in differing amounts, in either the forward and rearward directions, to steer or otherwise maneuver the work machine.
When directing some work machines in the forward and/or rearward direction the operator may need to maintain each electronic joystick in the operational position to keep the work machine traveling along the desired path. In some situations, it may be desirable for the operator to have a free hand to attend to other operations and control devices of the work machine. Accordingly, there is a need for an electronic joystick control system for controlling joystick position such that when each joystick is actuated in the operational position the operator may release the hand control on one of the joysticks and the electronic control system will maintain the released joystick position.
An operating device for a shift-by-wire transmission is disclosed in U.S. Pat. No. 8,413,533 entitled, “Operating Device Having Force Feedback,” (the '533 patent). The operating device is a lever rotatably coupled by a ball joint to a base of the transmission device. The '533 patent further includes a controllable counterforce element incorporating magnetorheological (MR) fluid and an actuator acting on the operating lever. The actuator provides active actuator-driven movement of the operating lever which automatically moves the operating lever into a certain lever position, for example automatically engaging the parking lock when the operator exits the vehicle. Furthermore, the MR fluid counterforce element is used to provide haptic feedback, or simulate the counterforces which a mechanical locking mechanism would produce in operation, while the actuator simulates the realistic return of the operating lever to the respective center positions of the locking mechanism when the operating lever is released.
While arguably effective, the '533 patent does not provide a control system of two operating devices that will allow the operator to release control of one operating device, while the control system maintains the position of the released operating device.